(a) Assistance upon Request; Authority. – Private persons may assist law-enforcement officers in effecting arrests and preventing escapes from custody when requested to do so by the officer. When so requested, a private person has the same authority to effect an arrest or prevent escape from custody as the officer making the request. He does not incur civil or criminal liability for an invalid arrest unless he knows the arrest to be invalid. Nothing in this subsection constitutes justification for willful, malicious or criminally negligent conduct by such person which injures or endangers any person or property, nor shall it be construed to excuse or justify the use of unreasonable or excessive force...

So in North Carolina in order for a private citizen to perform a lawful arrest he must be assisting an LEO, and only when requested by an LEO.

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"It is long been a principle of ours that one is no more armed because he has possession of a firearm than he is a musician because he owns a piano. There is no point in having a gun if you are not capable of using it skillfully." -- Jeff Cooper